A statistical method allowing comparisons of populations that takes into account age-distribution differences between populations. Most incidence and death data in SEER are age-adjusted, although some tables, in contrast, present the crude rate. Age-adjusting takes the 2000 US population distribution and applies it to other time periods under consideration. This assures that such rates do not reflect any changes in the population age distribution. Rates can be adjusted for the distribution of other characteristics such as race/ethnicity.

Most data in SEER have been age-adjusted to the 2000 US standard population. This allows comparison across racial groups taking into account differences in age structure of the populations. For example, the average age of many Hispanic/Latino populations is less than that of other racial/ethnic groups. Therefore, it sometimes appears that these groups have lower cancer incidence rates than other groups. However, by adjusting for age, more accurate comparisons can be made. See Calculating Age-adjusted Rates for further information.

The average annual percent change over several years. The APC is used to measure trends or the change in rates over time. For information on how this is calculated, go to Trend Algortihms in the SEER*Stat Help system. The calculation involves fitting a straight line to the natural logarithm of the data when it is displayed by calendar year.

An annual update of cancer death rates, incidence rates (new cases), and trends in the United States. The Centers for Disease Control and Prevention, the American Cancer Society, the National Cancer Institute, and the North American Association of Central Cancer Registries collaborate to create this report.

An estimate of the financial, emotional, or social impact that cancer creates within the population. Different racial, ethnic, geographic, and age groups in the United States do not share the burden of disease equally.

A joint effort by several organizations to develop standard computerized methods for determining the stage of cancer based on tumor size, extension of the primary tumor, lymph node involvement, and metastases. This algorithm allows one to obtain both the American Joint Committee on Cancer (AJCC) stage and the SEER historic stage. The AJCC stage is used clinically, but its definitions change over time. The definitions of the SEER historic stages have remained constant over time.

An estimated range of values which is likely to include an unknown population parameter. The 95% (p-value = .05) and 99% (p-value = .01) confidence intervals are the most commonly used.

If an estimated annual percentage change (APC) is -2.44 with a 95% confidence interval of (-2.83, -2.05), then we are 95% confident that the actual APC is between a decrease of -2.83% and a decrease of 2.05%. Inversely, there is still a 5% chance that the actual APC is not in the confidence interval (between the upper and lower confidence limits).

A crude rate is the ratio of the number of people in which the event of interest happens in a specified time period to the size of the population who may experience this event during the same time period. There are no adjustments made when a crude rate is given.

Fast Stats is designed to allow quick and easy access to key statistics for all major cancer sites by age, sex, race, and geographic area. The statistics include incidence, mortality, prevalence, and the probability of developing or dying from cancer.

At the time the World Health Organization's (WHO) International Agency for Research on Cancer (IARC) published their first monograph on Childhood Cancer in 1988, Dr. R. Marsden published an annex giving a classification scheme for childhood cancer that consisted of 12 groups based chiefly on histologic type. The classification by Marsden has been modified and is now called the International Classification of Childhood Cancers.